Re: [PATCH net-next] bonding: symmetric ICMP transmit
From: David Miller
Date: Sat Nov 16 2019 - 16:03:16 EST
From: Matteo Croce <mcroce@xxxxxxxxxx>
Date: Fri, 15 Nov 2019 12:10:37 +0100
> A bonding with layer2+3 or layer3+4 hashing uses the IP addresses and the ports
> to balance packets between slaves. With some network errors, we receive an ICMP
> error packet by the remote host or a router. If sent by a router, the source IP
> can differ from the remote host one. Additionally the ICMP protocol has no port
> numbers, so a layer3+4 bonding will get a different hash than the previous one.
> These two conditions could let the packet go through a different interface than
> the other packets of the same flow:
> An ICMP error packet contains the header of the packet which caused the network
> error, so inspect it and match the flow against it, so we can send the ICMP via
> the same interface of the previous packet in the flow.
> Move the IP and port dissect code into a generic function bond_flow_ip() and if
> we are dissecting an ICMP error packet, call it again with the adjusted offset.
> Signed-off-by: Matteo Croce <mcroce@xxxxxxxxxx>